/*
 * Copyright 2002-2012 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.aop.framework;

import org.aopalliance.intercept.Interceptor;
import org.aopalliance.intercept.MethodInterceptor;
import org.springframework.aop.Advisor;
import org.springframework.aop.IntroductionAdvisor;
import org.springframework.aop.MethodMatcher;
import org.springframework.aop.PointcutAdvisor;
import org.springframework.aop.framework.adapter.AdvisorAdapterRegistry;
import org.springframework.aop.framework.adapter.GlobalAdvisorAdapterRegistry;
import org.springframework.aop.support.MethodMatchers;

import java.io.Serializable;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

/**
 * A simple but definitive way of working out an advice chain for a Method,
 * given an {@link Advised} object. Always rebuilds each advice chain;
 * caching can be provided by subclasses.
 *
 * @author Juergen Hoeller
 * @author Rod Johnson
 * @author Adrian Colyer
 * @since 2.0.3
 */
@SuppressWarnings("serial")
public class DefaultAdvisorChainFactory implements AdvisorChainFactory, Serializable {

    /**
     * 此Advisor能否应用到目标方法method上，将满足条件的Advisor通过AdvisorAdapter转化为Interceptors列表返回
     *
     * @param config      the AOP configuration in the form of an Advised object
     * @param method      the proxied method
     * @param targetClass the target class
     * @return
     */
    public List<Object> getInterceptorsAndDynamicInterceptionAdvice(
            Advised config, Method method, Class targetClass) {

        // This is somewhat tricky... we have to process introductions first,
        // but we need to preserve order in the ultimate list.
        List<Object> interceptorList = new ArrayList<Object>(config.getAdvisors().length);
        //查看是否包含IntroductionAdvisor
        boolean hasIntroductions = hasMatchingIntroductions(config, targetClass);
        //这里实际上注册了一系列AdvisorAdapter，用于将Advisor转化为MethodInterceptor
        AdvisorAdapterRegistry registry = GlobalAdvisorAdapterRegistry.getInstance();
        for (Advisor advisor : config.getAdvisors()) {
            if (advisor instanceof PointcutAdvisor) {
                // Add it conditionally.
                PointcutAdvisor pointcutAdvisor = (PointcutAdvisor) advisor;

                if (config.isPreFiltered() || pointcutAdvisor.getPointcut().getClassFilter().matches(targetClass)) {
                    //此处这个地方这两个方法可以相互换交换下
                    //将Advisor转化为Interceptor
                    MethodInterceptor[] interceptors = registry.getInterceptors(advisor);

                    //检查当前advisor的pointcut是否可以匹配当前方法
                    MethodMatcher mm = pointcutAdvisor.getPointcut().getMethodMatcher();
                    if (MethodMatchers.matches(mm, method, targetClass, hasIntroductions)) {
                        if (mm.isRuntime()) {
                            // Creating a new object instance in the getInterceptors() method
                            // isn't a problem as we normally cache created chains.
                            for (MethodInterceptor interceptor : interceptors) {
                                interceptorList.add(new InterceptorAndDynamicMethodMatcher(interceptor, mm));
                            }
                        } else {
                            interceptorList.addAll(Arrays.asList(interceptors));
                        }
                    }
                }
            } else if (advisor instanceof IntroductionAdvisor) {
                IntroductionAdvisor ia = (IntroductionAdvisor) advisor;
                if (config.isPreFiltered() || ia.getClassFilter().matches(targetClass)) {
                    Interceptor[] interceptors = registry.getInterceptors(advisor);
                    interceptorList.addAll(Arrays.asList(interceptors));
                }
            } else {
                Interceptor[] interceptors = registry.getInterceptors(advisor);
                interceptorList.addAll(Arrays.asList(interceptors));
            }
        }
        return interceptorList;
    }

    /**
     * Determine whether the Advisors contain matching introductions.
     */
    private static boolean hasMatchingIntroductions(Advised config, Class targetClass) {
        for (int i = 0; i < config.getAdvisors().length; i++) {
            Advisor advisor = config.getAdvisors()[i];
            if (advisor instanceof IntroductionAdvisor) {
                IntroductionAdvisor ia = (IntroductionAdvisor) advisor;
                if (ia.getClassFilter().matches(targetClass)) {
                    return true;
                }
            }
        }
        return false;
    }

}
